Polymerisates of ethylene with a high degree of resistance to stress crack, and a catalyst system for the production thereof

ABSTRACT

Polymers of ethylene are obtainable by polymerization of ethylene and, if desired, further comonomers in the presence of a catalyst system comprising as active constituents 
     I) a Phillips catalyst, 
     II) a solid which is different from I) and comprises a component which is derived from the metallocene complexes of the formula (A) in which the substituents and indices have the following meanings:                    
      R 1  to R 10  are hydrogen, C 1 -C 10 -alkyl, 5-to 7-membered cycloalkyl which may in turn bear C 1 -C 6 -alkyl groups as substituents, C 6 -C 15 -aryl or aryalkyl, where two adjacent radicals may also together form a cyclic group having from 4 to 15 carbon atoms, or Si(R 11 ) 3 , where R 11  is C 1 -C 10 -alkyl, C 6 -C 15 -aryl or C 3 -C 10 -cycloalkyl, or the radicals R 4  and R 9  together form a group —[Y(R 12 R 13 )] m —, where Y is silicon, germanium, tin or carbon, and R 12 , R 13  are hydrogen C 1 -C 10 -alky, C 3 -C 10 -cycloalyl or C 6 -C 15 -aryl, 
     M is a metal of transition groups IV to VIII or a metal of the lanthanide series, 
     Z 1 , Z 2  are fluorine, chlorine, bromine, iodine, hydrogen, C 1 -C 20 -alkyl or aryl, —OR 14 , —OOCR 14 ,                    
      where R 14  is hydrogen or C 1 -C 20 -alkyl; R 15  is C 1 -C 20 -alkyl; m is 1,2,3 or 4; n is 0, or 2; r is 0, 1 or 2; the sum n+r is likewise 0, 1 or 2, and, if desired, 
     III) an organometallic component selected from groups IA, IIA, IIB and IIIA of the Periodic Table of the Elements.

The present invention relates to polymers of ethylene obtainable bypolymerization of ethylene and, if desired, further comonomers in thepresence of a catalyst system comprising as active constituents

I) a Phillips catalyst,

II) a solid which is different from I) and comprises a component whichis derived from the metallocene complexes of the formula (A) in whichthe substituents and indices have the following meanings:

 R¹ to R¹⁰ are hydrogen, C₁-C₁₀-alkyl, 5- to 7-membered cycloalkyl whichmay in turn bear C₁-C₆-alkyl groups as substituents, C₆-C₁₅-aryl orarylalkyl, where two adjacent radicals may also together form a cyclicgroup having from 4 to 15 carbon atoms, or Si(R¹¹)₃,

where R¹¹ is C₁-C₁₀-alkyl, C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl, or theradicals R⁴ and R⁹ together form a group —[Y(R¹²R¹³]_(m)—,

 where Y is silicon, germanium, tin or carbon,

R¹², R¹³ are hydrogen, C₁-C₁₀-alkyl, C₃-C₁₀-cycloalkyl or C₆-Cl₅-aryl

M is a metal of transition groups IV to VIII or a metal of thelanthanide series,

Z¹, Z² are fluorine, chlorine, bromine, iodine, hydrogen, C₁-C₂₀-alkylor aryl, —OR¹⁴, —OOCR¹⁴,

 where R¹⁴ is hydrogen or C₁-C₂₀-alkyl,

R¹⁵ is C₁-C₂₀-alkyl,

m 1, 2, 3 or 4

n 0, 1 or 2

r 0, 1 or 2,

where the sum n+r is likewise 0, 1 or 2,

and, if desired,

III) an organometallic component selected from groups IA, IIA, IIB andIIIA of the Periodic Table of the Elements.

The invention further relates to catalyst systems which are suitable forthe polymerization of ethylene and, if desired, further comonomers, aprocess for preparing the polymers of ethylene and the use of thepolymers of ethylene for producing films, moldings and fibers and alsothe films, moldings and fibers.

Moldings and films are frequently produced from polyethylene.Polyethylene moldings are used, for example, as plastic fuel containers(tanks), containers for the transport of dangerous goods or as pressurepipes for gas and water. In these applications, the moldings should notrupture under stress, or in other words their environmental stress crackresistance should be as high as possible. In addition, the moldingsshould display little deformation under the action of external force,which means that their stiffness should be as great as possible.

Ethylene polymers whose processing leads to moldings having a relativelyhigh environmental stress crack resistance and a relatively highstiffness can, as described in EP-A 0 533 155 and EP-A 0 533 156, beobtained by mixing ethylene polymers which have been prepared, on theone hand, using Ziegler catalysts and, on the other hand, using Phillipscatalysts. However, this process is complicated because each polymercomponent has to be prepared on its own using different catalysts inseparate reactors and the components have to be mixed in a separatestep.

WO-A 92/17511 describes the polymerization of ethylene in the presenceof two Phillips catalysts which differ in their pore volume. However,the properties of the polymers obtained here leave something to bedesired. This applies particularly to the relationship of stiffness andenvironmental stress crack resistance of the moldings produced fromthem.

It is an object of the present invention to provide novel ethylenepolymers which do not have the stated disadvantages, or have them toonly a small degree, and which are suitable for producing moldingshaving a good environmental stress crack resistance and a highstiffness.

We have found that this object is achieved by the ethylene polymers andcatalyst systems defined at the outset. In addition, we have found aprocess for preparing the ethylene polymers and also the use of theethylene polymers for producing films, moldings and fibers and also thefilms, moldings and fibers.

The ethylene polymers of the present invention usually have a 35density, measured in accordance with DIN 53479, in the range from 0.925to 0.965 g/cm³, preferably in the range from 0.945 to 0.955 g/cm³, and amelt flow rate (MFR), measured in accordance with DIN 53735 underdifferent loads (in brackets), in the range from 0.0 (190° C./21.6 kg)to 200 (190° C./2.16 kg) g/10 min, preferably in the range from 2.0(190° C./21.6 kg) to 50 (190° C./21.6 kg) g/10 min.

The weight average molecular weight Mw is generally in the range from10,000 to 7,000,000, preferably in the range from 20,000 to 1,000,000.The molecular weight distribution Mw/Mn, measured by GPC (gel permeationchromatography) at 135° C. in 1,2,4-trichlorobenzene relative to apolyethylene standard, is usually in the range from 3 to 300, preferablyin the range from 8 to 30.

In general, the ethylene polymers produced in the reactor are melted andhomogenized in an extruder. The melt flow rate and the density of theextrudate can then differ from the corresponding values for the rawpolymer, but remain in the range according to the present invention.

The catalyst systems of the present invention comprise a mixture of thesolid components I) and II) of different types which can be preparedseparately and, if desired, organometallic compounds III) of the first(IA), second (IIA) and third (IIIA) main group or the second (IIB)transition group of the Periodic Table of the Elements, which generallyfunction as activators. It is also possible to use mixtures of theorganometallic compounds III).

To prepare the solid components I) and II), a support material isgenerally brought into contact with one or more compound(s) containingthe appropriate transition metal.

The support material is usually a porous inorganic solid which may stillcontain hydroxy groups. Examples of such solids, which are known tothose skilled in the art, are aluminum oxide, silicon dioxide (silicagel), titanium dioxide or their mixed oxides, or aluminum phosphate.Further suitable support materials can be obtained by modifying the poresurface with compounds of the elements boron (BE-A-61,275), aluminum(U.S. Pat. No. 4,284,5,27), silicon (EP-A 0 166 157), phosphorus (DE-A36 35 715) or titanium. The support material can be treated underoxidizing or nonoxidizing conditions at from 200 to 1000° C., in thepresence or absence of fluorinating agents such as ammoniumhexafluorosilicate.

The polymerization-active component of type I) is a customary Phillipscatalyst known to those skilled in the art whose preparation isdescribed, for example, in DE-A 25 40 279 or DE-A 39 38 723. Describedin a simplified way, it is generally obtained by impregnating a supportmaterial, for example silica gel, with a chromium-containing solution,evaporating the solvent and heating the solid under oxidizingconditions, for example in an oxygen-containing atmosphere, at from 400to 1000° C. This activation can be followed by a reduction which can,for example, be carried out by treating the chromium-containing solidwith carbon monoxide at from 20 to 800° C. The preparation process forI) thus generally comprises at least one oxidizing step.

The polymerization-active component II) of the catalyst systems of thepresent invention differs from the component I) in that, inter alia, anorganometallic compound of a transition metal is generally applied to asupport material in the preparation of II) and the subsequent treatmentof the solid under oxidizing conditions is omitted. The support materialcan be calcined at from 50 to 1000° C. before treatment with theorganometallic transition metal compound. It is also possible fororganometallic compounds III), preferably aluminum alkyls having from 1to 10 carbon atoms, in particular trimethylaluminum, triethylaluminum oraluminoxanes, to be applied to the support materials.

To prepare the component II), a metal complex of the formula (A) isgenerally dissolved in a solvent, for example an aliphatic or aromatichydrocarbon or an ether, and mixed with the support material. Preferenceis given to using hexane, heptane, toluene, ethylbenzene,tetrahydrofuran or diethyl ether as solvent and silica gel, aluminumoxide or aluminum phosphate as support material.

The solvent is removed from the resulting suspension, usually byevaporation.

It is also possible to mix the metal complex (A) with one or moreorganometallic compounds of the component (III), in particularC₁-C₄-trialkylaluminums, eg. trimethyl aluminum or triethylaluminum, orwith methylaluminoxane, before contact with the support material andthen to bring the mixture into contact with the support material.

Furthermore, suitable complexes (A) can be deposited from the gas phaseonto the support material by sublimation. For this purpose, thecomplexes (A) are generally mixed with the support material, for examplesilica gel, aluminum oxide or aluminum phosphate, and heated to from 0to 200° C. at a pressure in the range from 0.00001 to 100 kPa. In thisprocess, preference is given to using chromium-containing complexes (A)and, in particular, unsubstituted or substitutedbis(cyclopentadienyl)chromium compounds.

The transition metal content of the component II) is generally in therange from 1 to 1000 μmol of transition metal/g of solid, preferably inthe range from 10 to 500 μmol of transition metal/g of solid.

In the metal complex (A)

M is a metal of the 4th to 8th transition groups (IVB to VIIIB) or ofthe lanthanide series of the Periodic Table of the Elements, preferablytitanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium,molybdenum, tungsten, manganese, iron, ruthenium, osmium, cobalt ornickel and very particularly preferably titanium, zirconium, hafnium orchromium.

R¹ to R¹⁰ are hydrogen, C₁-C₁₀-alkyl, 5- to 7-membered cycloalkyl whichmay in turn bear C₁-C₆-alkyl groups as substituents, C₆-C₁₅-aryl orarylalkyl, where two adjacent radicals may also together form a cyclicgroup having from 4 to 15 carbon atoms (ring fusion), or Si(R¹¹)₃, whereR¹¹ is C₁-C₁₀-alkyl, C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl or the radicals R⁴and R⁹ together form a group —[Y(R¹²R¹³]_(m)—, where Y is silicon,germanium, tin or carbon, R¹², R¹³ are hydrogen, C₁-C₁₀-alkyl,C₃-C₁₀-cycloalkyl or C₆-C₁₅-aryl.

R¹ to R¹⁰ are preferably hydrogen, methyl, ethyl, n-propyl, iso-propyl,n-butyl, tert-butyl, a fused-on 6- or 7-membered carbocyclic ring systemand/or a bridge —[Y(R¹²R¹³)]_(m)—. In particular, R¹ to R¹⁰ arehydrogen, methyl, n-butyl or a fused-on 6-membered ring system(indenyl-type ligand) and/or a bridge —[Y(R¹²R¹³)]_(m)—. Preferredbridges —[Y(R¹²R¹³)]_(m)— are those where Y is carbon or silicon; R¹²,R¹³ are then hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl,tert-butyl or phenyl and m is preferably 1 or 2.

Z¹, Z² in (A) are fluorine, chlorine, bromine, iodine, hydrogen,C₁-C₂₀-alkyl or aryl, preferably C₁-C₂₀-aliphatic radicals,C₃-C₁₀-cycloaliphatic radicals, C₆-C₁₅-aromatic radicals or aralkylradicals having from 6 to 15 carbon atoms in the aryl radical and from 1to 10 carbon atoms in the alkyl radical. Examples which may be mentionedare methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, tert-butyl,iso-butyl, cyclopentyl, cyclohexyl, phenyl, tolyl and benzyl.

Z¹, Z² may also be alkoxide (—OR¹⁴), carboxylate (—OOCR¹⁴), aldolate

or derivatives of the cyclopentadienyl radical

where R¹ to R¹⁰ are as defined above.

R¹⁴, R¹⁵ are hydrogen, C₁-C₂₀-alkyl, preferably methyl, ethyl,iso-propyl or tert-butyl.

Z¹, Z² in (A) are preferably hydrogen, chlorine, methyl or phenyl, inparticular chlorine.

The index m in (A) is 1, 2, 3 or 4, preferably 1 or 2 and inparticular 1. A very preferred bridge is the dimethylsilyl group.

The indices n and r in (A) are 0, 1 or 2, where the sum n+r is likewise0, 1 or 2. Preferably, n and r are 0, 1 or 2 and the sum n+r ispreferably 0 or 2.

Well suited compounds of the formula (A) are complexes containingunsubstituted or substituted bis(cyclopentadienyl) or bis(indenyl)ligands, and also complexes containing bridged substituted orunsubstituted indenyl ligands, as are described, for example, in DE-C 4344 672.

Examples of preferred metallocene complexes of the formula (A) aredimethylsilylbis(2-methylbenzindenyl)zirconium dichloride,bis(cyclopentadienyl)zirconium dichloride,bis-(pentamethylcyclopentadienyl)zirconium dichloride,bis(n-butylcyclopentadienyl)zirconium dichloride,bis(cyclopentadienyl)chromium, bis(pentamethylcyclopentadienyl)chromium,bis(indenyl)chromium and bis(fluorenyl)chromium.

In particular, compounds (A) used aredimethylsilylbis(2-methylbenzindenyl)zirconium dichloride,bis(pentamethylcyclopentadienyl)zirconium dichloride orbis(cyclopentadienyl)chromium.

The catalyst components I) and II) can generally be selected freely, butpreference is given to catalyst systems whose individual components I)and II) differ in their copolymerization behavior toward a monomermixture of ethylene/comonomer.

The copolymerization behavior can be described by the equation

R=(b−1)/a

where b is the molar ratio of the derived structural units(ethylene:comonomer) in the copolymer and a is the molar ratio ofethylene to comonomer in the monomer mixture in the reactor.

Well suited combinations I) and II) are generally those whose R valuesof the individual components differ by a factor of 2 or more, inparticular those whose R values differ by a factor of 4 or more.

The polymers of the present invention can be obtained byhomopolymerization of ethylene or by copolymerization of ethylene withone or more other monomers in the presence of the catalyst componentsI), II) and, if desired, III).

Useful comonomers are usually C₃-C₁₅-alk-1-enes, for example propene,1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene,1-dodecene or 1-pentadecene. Preference is given to using 1-butene,1-hexene or 1-octene and in particular 1-hexene.

The chemically bound proportion of comonomer in the copolymers isgenerally in the range from 0.1 to 2 mol %, preferably from 0.3 to 1.5mol %, based on the copolymer.

The polymerizations can be carried out by the known methods customaryfor the polymerization of olefins, for example solution processes,suspension processes, stirred gas phase or gas-phase fluidized-bedprocesses, continuously or batchwise. Solvents or suspension media whichcan be used are inert hydrocarbons such as iso-butane or else themonomers themselves.

The pressure is generally from 100 to 10,000 kPa, preferably from 1000to 6000 kPa and the temperature is generally in the range from 10 to150° C., preferably in the range from 30 to 125° C.

Particularly well suited processes for preparing the polymers of thepresent invention are the suspension process and the gas-phasefluidized-bed process. The particular catalyst composition makes itpossible to obtain the polymers of the present invention from a singlereactor.

The catalyst components I) and II) can be mixed before they come intocontact with the monomers and then metered jointly into the reactor orthey can be metered into the reactor separately from one another, forexample at a plurality of points.

The polymerization can advantageously be carried out in the presence ofan organometallic component III) selected from groups IA, IIA, IIB andIIIA of the Periodic Table of the Elements. Suitable compounds III) are,for example, lithium, boron, zinc or aluminum C₁-C₁₀-alkyls or alkylhydrides, or else C₁-C₄-alkylaluminoxanes, which are described, forexample, in EP-A 284 708. Very well suited compounds of this type are,for example, n-butyllithium, triethylboron,tris(pentafluorophenyl)boron, triethylaluminum, trihexylaluminum,diisobutylaluminum hydride and methylaluminoxane. Ifbis(cyclopentadienyl)chromium or one of its substituted cyclopentadienylderivatives is used as component II), n-butyllithium is particularlyuseful as component III).

The molar ratio of organometallic component III) to transition metal isgenerally from 1000:1 bis 0.01:1, preferably from 500:1 to 1:1.

As molar mass regulator, use is generally made of hydrogen, preferablywhen using components II) which contain metals of group IVB or VIB, eg.zirconium or chromium. In the absence of hydrogen, the molar mass of thepolymers can be influenced by varying the reaction temperature.

The polymers of the present invention have a high environmental stresscrack resistance at the same time as a high stiffness (density). Theyare well suited to producing components which have to have a highenvironmental stress crack resistance and a high stiffness, inparticular pressure pipes for gas or water. Furthermore, they can beadvantageously used for coating pipes and for producing cable sheathing.

EXAMPLES

Catalyst Preparation

Example 1 Component I

116.5 g of chromium trinitrate nonahydrate (0.29 mol) and 37.5 g ofdiammonium hexafluorosilicate (0.21 mol) were added to a suspension of1.5 kg of a silica gel (SD 32 16 from Grace) in 8 l of water and themixture was stirred for 1 hour at 25° C. The water was subsequentlyremoved at 100° C. under reduced pressure and the solid was treated at550° C. in a stream of air for two hours.

Component IIa) (chromium-containing)

General Procedure

Silica gel (SG 332 from Grace) was calcined at 800° C. in a stream ofargon for six hours and was then brought into contact withbis(cyclopentadienyl)chromium (chromocene) in three different variants Ato C (see below).

Variant A

4 g (0.02 mol) of bis(cyclopentadienyl)chromium were added to asuspension of 60 g of calcined silica gel in 500 ml of heptane and thesolvent was subsequently removed. Chromium content of the solid: 1.9% byweight.

Variant B

60 g of calcined silica gel were mixed dry with 4 g (0.02 mol) ofbis(cyclopentadienyl)chromium, the pressure in the reaction vessel wasthen reduced to 0.01 kPa and was maintained for two hours; during thistime, the bis(cyclopentadienyl)chromium deposited on the silica gel.Chromium content of the solid: 1.9% by weight.

Variant C

The procedure of Variant B was repeated, but the catalyst solid obtainedwas heated at 80° C. for 2.5 hours. Chromium content of the solid: 1.9%by weight.

Component IIb) (zirconium-containing)

1.19 g (0.0021 mol) ofrac-dimethylsilanediylbis(2-methylbenzindenyl)zirconium dichloride weredissolved at room temperature in 538.5 ml of a 1.53 molar solution ofmethylaluminoxane in toluene (0.82 mol). 100 g of a silica gel SG 332(25-40 μm) from Grace calcined at 800° C. in a stream of argon wereslowly introduced into this solution and the solvent was subsequentlyevaporated.

Polymerizations

Examples 2 and 3 (ethylene/1-hexene copolymerization)

The polymerizations were carried out in a 180 l Phillips suspension loopreactor using iso-butane as suspension medium. The catalyst componentsI) and IIa) (Example 1) were added from two different metering-inpoints. The catalyst component IIa) was prepared as described in Example1, Variant B. The polymerization was carried out in the presence ofn-butyllithium (0.063 molar in heptane) as component III) and usinghydrogen as molar mass regulator. The reactor was initially charged withthe monomers, cocatalyst and suspension medium and the polymerizationwas started by metering in the catalyst components I) and IIa) and wasthen conducted continuously. The polymer was subsequently granulated bymeans of an extruder. The process parameters are shown in Table 1, theproduct properties are shown in Table 2.

TABLE 1 Process parameters Example 2 3 Hydrogen [% by vol.] 0.31 0.57Ethylene [% by vol.] 18.1 12.8 1-Hexene [% by vol.] 2.0 1.3 Reactiontemp. [° C.] 97.6 97.5 n-Butyllithium [g/h] 0.31 0.31 Productivity[g/g]^(a)) 5600 5000 ^(a))g of polymer/g of catalyst solid

TABLE 2 Polymer properties Example 2 3 Density [g/cm³]^(b)) 0.94760.9467 MFR [g/10 min]^(c)) 5.6 6.7 ESCR [h]^(d)) >200 >200^(b))determined in accordance with DIN 53479 ^(c))Melt flow rate at 190°C. and a load of 21.6 kg, determined in accordance with DIN 53735^(d))Environmental stress crack resistance, determined by BASF's ownmethod. Here, the polymer is pressed to form a 1 mm thick plate fromwhich disks having a diameter of 38 mm are stamped. These disks areprovided on one side with a 200 μm deep, 3 cm long notch. The plates aredipped into a 5% strength surfactant solution (Lutensol ® FSA) which isat 50° C., and a pressure of 3 bar is applied on one side of the #plates. The time from application of pressure to fracture of the disk ismeasured. The arithmetic mean of five measurements is calculated.

Comparative example

The ESCR of an ethylene/1-hexene copolymer (0.004 mol % of units derivedfrom 1-hexene, d=0.9465 g/cm³) obtained using a conventional Phillipscatalyst as described in DE-A 25 40 279 (example) was measured. It was118 hours.

The polymers of the present invention prepared as described in Examples2 and 3 have a higher environmental stress crack resistance than thepolymer of the comparative experiment while the density is at least ashigh.

Examples 4 and 5

General

A 1 l autoclave was charged with 500 ml of isobutane, 5 ml of 1-hexene(0.04 mol) and 20 mg of n-butyllithium (0.063 molar in heptane). Thecontents of the autoclave were heated to 80° C., the pressure wasincreased by means of ethylene to 4000 kPa and 40 mg of each of thecatalyst solids I) and IIb) were metered in and the polymerization wascarried out for 90 minutes.

Example 4

Here, the catalyst component I) was metered in first and the componentIIb) (Example 1) was then metered in. 104 g of polymer were obtained,corresponding to a productivity of 1300 g of polymer/g of catalystsolid. The density of the polymer was 0.935 g/cm³ and the MFR (190°C./21.6 kg) was 0.0 g/10 min.

Example 5

The procedure of Example 4 was repeated except that the component IIb)was metered in first followed by the component I). 123 g of polymer wereobtained, corresponding to a productivity of 1540 g of polymer/g ofcatalyst solid. The density of the polymer was 0.9280 g/cm³ and the MFR(190° C./21.6 kg) was 0.0 g/10 min.

We claim:
 1. A polymer of ethylene obtained by polymerization ofethylene or ethylene and further comonomers in the presence of acatalyst system comprising as active constituents I) a Phillipscatalyst, II) a solid which is different from I) and comprises a silicagel support and a component which is derived from the metallocenecomplexes of the formula (A) in which the substituents and the indiceshave the following meanings:

 R¹ to R¹⁰ are hydrogen, C₁-C₁₀-alkyl, 5- to 7-membered cycloalkyl whichmay in turn bear C₁-C₆-alkyl groups as substituents, C₅-C₁₅-aryl orarylalkyl, where two adjacent radicals may also together form a cyclicgroup having from 4 to 15 carbon atoms, or Si(R¹¹)₃, where R¹¹ isC₁-C₁₀-alkyl, C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl, or the radicals R⁴ andR⁹ together form a group —[Y(R¹²R¹³]_(m)—, where Y is silicon,germanium, tin or carbon R¹², R¹³ are hydrogen, C₁-C₁₀-alkyl,C₃-C₁₀-cycloalkyl or C₆-C₁₅-aryl M is a metal of transition groups IV toVIII or a metal of the lanthanide series, Z¹, Z² are fluorine, chlorine,bromine, iodine, hydrogen, C₁-C₂₀-alkyl or aryl, —OR¹⁴, —OOCR¹⁴,

R¹⁴ is hydrogen or C₁-C₂₀-alkyl, R¹⁵ is C₁-C₂₀-alkyl, m 1, 2, 3 or 4 n0, 1 or 2 r 0, 1 or 2, where the sum n+r is likewise 0, 1 or 2, andoptionally III)an organometallic component selected from groups IA, IIA,IIB and IIIA of the Periodic Table of the Elements.
 2. The polymerdefined in claim 1, wherein M in (A) is zirconium or chromium.
 3. Thepolymer defined in claim 1 which has a density in the range from 0.925to 0.965 g/cm³.
 4. The polymer defined in claim 1 comprisingC₃-C₁₅-alk-1-enes as comonomers.
 5. A catalyst system comprising asactive constituents I) a Phillips catalyst, II) a solid which isdifferent from I) and comprises a silica gel support and a componentwhich is derived from the metallocene complexes of the formula (A) inwhich the substituents and the indices have the following meanings:

 R¹ to R¹⁰ are hydrogen, C₁-C₁₀-alkyl, 5- to 7-membered cycloalkyl whichmay in turn bear C₁-C₆-alkyl groups as substituents, C₅-C₁₅-aryl orarylalkyl, where two adjacent radicals may also together form a cyclicgroup having from 4 to 15 carbon atoms, or Si(R¹¹)₃, where R¹¹ isC₁-C₁₀-alkyl, C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl, or the radicals R⁴ andR⁹ together form a group —[Y(R¹²R¹³]_(m)—, where Y is silicon,germanium, tin or carbon R¹² ₁ R¹³ are hydrogen, C₁-C₁₀-alkyl,C₃-C₁₀-cycloalkyl or C₆-C₁₅-aryl M is a metal of transition groups IV toVIII or a metal of the lanthanide series, Z¹, Z² are fluorine, chlorine,bromine, iodine, hydrogen, C₁-C₂₀-alkyl or aryl, —OR¹⁴, —OOCR¹⁴,

R¹⁴ is hydrogen or C₁-C₂₀-alkyl, R¹⁵ is C₁-C₂₀-alkyl, m 1, 2, 3 or 4 n0, 1 or 2 r 0, 1 or 2, where the sum n+r is likewise 0, 1 or 2, andoptionally III) an organometallic component selected from groups IA,IIA, IIB and IIIA of the Periodic Table of the Elements.
 6. The catalystsystem defined in claim 5, wherein M in (A) is zirconium or chromium. 7.The catalyst system defined in claim 5, wherein (A) is a zirconiumcomplex containing a bridged, substituted or unsubstituted indenylligand.
 8. A process for preparing polymers of ethylene or ethylene andfurther comonomers as defined in claim 1, which comprises polymerizingethylene and optionally further comonomers in the presence of thecatalyst system.
 9. A process for producing films, moldings and fibers,comprising extruding a polymer as claimed in claim
 1. 10. A film,molding or fiber comprising a polymer as claimed in of claim 1.